MIAMI — Tropical Storm Karen has formed in the Gulf of Mexico, and a hurricane watch is in effect along the Gulf Coast from Louisiana to Florida.

The U.S. National Hurricane Center in Miami says the late-season storm formed this morning. It was about 500 miles south of the mouth of the Mississippi River and already had maximum sustained winds of 60 mph.

The hurricane watch was in effect from Grand Isle, La., to Indian Pass in the Florida Panhandle. A tropical storm watch also was in effect for parts of the Louisiana coast west of Grand Isle, including the metro New Orleans area and Lake Pontchartrain.

Karen was moving north-northwest at 13 mph. It could be at or near hurricane strength by Friday.